Fate of 200 American ISIS Members Unknown

An estimated 300 Americans attempted to join ISIS and other extremist groups in Iraq and Syria, but the fate of around 200 of them is unknown, according to a US report.

So far, 12 of those Americans have returned home, yet none has carried out an attack on US soil, said the report released this week by George Washington University's Program on Extremism.

“There was always concern that this wave of what the FBI would call 'the terrorist diaspora' would come back. In many ways it's just a trickle right now," said Seamus Hughes, one of the report's authors.

The report covers the period since 2011, when the Syria war erupted. ISIS peaked, in terms of power and territory, in the summer of 2014, when it held large parts of Syria and Iraq.

Around 50 Americans were arrested as they tried to leave the country, and never made it out of the US. The report was able to document 64 individuals who did reach the two Arab states.

They include Zulfi Hoxha, a New Jersey resident of Albanian descent.

He traveled to Syria in 2015, and US authorities have described him as a "senior ISIS commander." He appears in two ISIS propaganda videos, including one where he beheads a prisoner.

Of the 12 Americans who returned, nine were arrested and remain in custody, the report said. Two others are known to law enforcement, but have not been detained, it added. The 12th man went back to Syria a second time and carried out a suicide bombing, the report said.

While no American has returned and carried out an attack, one man, Abdirahman Sheik Mohamud of Ohio, planned to do so.

He was among a small number of Americans to join al-Nusra Front in Syria, an extremist group linked to al-Qaeda. One of his commanders sent him back to Ohio with orders to attack a US military facility.

Mohamud returned to the US State in 2014, and was arrested the following year. He pleaded guilty to plotting the attacks and in January was sentenced to 22 years in prison.

The report did not deal with those who may have been inspired by ISIS and acted inside the US.